This is annoying. It's similar to a priest, "you healing?" "No I'm shadow".
I understand you're not specced to tank, and though i've never done it, leveling as a prot warrior doesn't sound fun.
But you can still tank!
I've leveled up a 65 warrior, fury the entire way and i tanked instances just fine. Including BRD, ramparts, underbog, and i think mana tombs. It wasn't as smooth as a prot warrior would've done, but they were all still completed.
Tank and healer are the hardest people to find for a group. I found it incredibly annoying healing instances with my ret paladin and he leveled, but i did it anyways for the greater good.
And i accepted tanking and was succesful at it as a fury warrior.
Really, the only "Tank" i expect to have that is specced to tank pre-70 is a Paladin. And really, who wouldn't rather have a paladin tank than a warrior tank?
haha oh man.
/fin